1. Field of the Invention
This invention relates generally to the field of focal plane imaging devices and, more particularly, to an imaging system employing variable acuity super-pixel imaging that also provides analog signals representative of pitch, roll and yaw angle rates by image motion analysis.
2. Description of the Related Art
Sensing high spatial resolution imagery at very high frame rates, covering wide fields of view while at the same time producing a low data bandwidth so as not to overload data transmission “pipes” is problematic in current imaging systems. As an example, in current “megapixel” imaging systems; high frame rates (e.g., higher than 1000 frames per second) would produce pixel rates in excess of one billion pixels per second; high dynamic range representations of pixels (e.g., 16 bits per pixel, or two bytes per pixel) would produce in excess of two billion bytes per second, or 32 billion bits per second.
Prior imaging systems have been disclosed in U.S. Pat. No. 5,949,483 to Fossum entitled “Active pixel sensor array with multiresolution readout”, U.S. Pat. No. 5,430,294 to Mears entitled “Staring focal plane array architecture for multiple applications” and U.S. Pat. No. 5,541,654 to Roberts entitled “Focal plane array imaging device with random access architecture”. Fossum discloses use of variable acuity in imaging systems but limits the number of acuity regions and requires that they be of rectangular shape. In addition, spatial agglomeration of pixel values in Fossum's implementation is performed in the column region of the integrated circuit imposing a speed limitation on the number of frames per second which may be produced because all analog pixel values must be shifted out of the unit cell region before such pixel combination is performed. The “windowing” features as represented in Mears' work permits high-speed image sampling, but image regions outside of the desired window are simply ignored.
It is therefore desirable to provide an imager having the capability to permit its pixels be spatially reconfigured and combined, resulting in very high frame rates. It is also desirable to provide the user the ability to produce virtually any spatial configuration. It is also desirable to collect photocharge in temporal “snapshot” mode, guaranteeing temporal coincidence for every pixel in the imager. It is further desirable to permit such updates to take effect without dropping any frames of image data and to produce high-speed, high-relevance imagery, as well as to digitally report its instantaneous spatial configuration. It is also further desirable to provide the ability to mate a variety of detector array types, for applicability to a wide spectral range of useful imaging wavelengths. Also desirable is the ability to measure the roll, pitch and yaw angle rates of background imagery using on-chip circuitry. Finally, it is desirable to perform all desired functions in an integrated circuit that consumes extremely low power and has an extremely low mass.